The present invention concerns a device for decreasing the number of antennas on a combat vehicle that accommodates several communications terminals.
The demand for effective communications in military applications has been increasing rapidly quite recently. This demand concerns both the classical stationary communications equipment and mobile communications devices. Because of these developments, it has been necessary to equip contemporary combat vehicles with a number of communications terminals. This equipment not only transmits information in general but also handles communications (data and voice) between individual components of the system. The statistical individuality of the data thereby transmitted makes it impossible to establish an overall format for the traffic between different communications systems. In principle, however, all the radio equipment must be capable of operating parallel, even within a single frequency range when necessary.
Contemporary combat vehicles are usually provided with two separate antennas in the stern. Physical conditions often make it desirable to mount an antenna systems-engineering optimally on the vehicle, although this is impossible when there are several such components.
The object of the present invention is accordingly a device that will by simple means allow a decrease in the number of antennas on the vehicle and especially the use of only one antenna, which can accordingly be installed optimally from the systems-engineering aspect, instead of two.
Several engineering goals had to be attained here:
a) non-priority parallel exploitation of a single antenna, with several radios accessing it simultaneously, a slight decrease in range being permissible,
b) a diplexer capable of transmittingxe2x80x94in accordance with the radio""s specificationsxe2x80x94a high-frequency signal in the 30-110 MHz range,
c) high-frequency output with the diplexer forwardingxe2x80x94in accordance with the radio""s specificationsxe2x80x9450 watts per adapted radio,
d) high-frequency decoupling of parallel ports, the manufacturer""s decoupling specifications being absolutely complied with when several radios are coupled to the same antenna, whereby failure to attain the specifications would lead directly to destruction of the receiver""s input stages,
e) direct-current (antenna-to-radio) coupling, ensuring transmission of 50 volts from the radio to the base of the antenna, this voltage acting as a bias voltage for a diode network to protect the system from lightning, and
f) direct-current decoupling (radio-from-radio) of the individual radios"" 50 V DC current, ensuring suppression of any DC equalizing current by way of the antenna input terminals.
The aforesaid object is attained in accordance with the present invention in that each pair of communications terminals is coupled to the same antenna by way of a combiner-separator module, each module comprising one master gate for connecting the antenna and two slave gates for connecting the communications terminals, coupled by way of a transformer stage, whereby the gates are direct-current decoupled from the transformer stage and the master gate is connected to each slave gate by way of a bypass that transmits strictly a direct current and provides an antenna voltage.
It has been demonstrated of advantage here for the transformer stage to comprise a transformer with one end of its primary coil connected to the master gate by way of a capacitor and the other end connected to zero potential and with both ends of its secondary coil connected to one of the slave gates by way of a capacitor and to zero potential at a branch at the midpoint.
According to the theory basic to the present invention, two communications terminals can be connected to a single antenna by way of a special combiner-separator module, and the aforesaid engineering problems can be solved by providing the module with a passive diplexer modified to comply with the aforesaid specifications.
As will be specified hereinafter with reference to a particular embodiment, the combiner-separator module in accordance with the present invention will easily allow the connection of two communications terminals to a single antenna while still complying with the aforesaid conditions.